In this paper, a method to calculate the inclination function with Jacobi polynomials is introduced. Its expressions are very simple. With this method, it is unnecessary to distinguish whether k and l have the same parity, to calculate the non-integral factorial, and to convert from k < 0 to k≧ 0. We can use the standard Jacobi polynomial program to compute inclination function. Its accuracy is the same as Gooding's method, and the computing time is 9% less than Gooding's.